JP-2007-113420A shows a fuel-property reforming apparatus which is provided with a reforming-fuel injector which injects a reforming-fuel into intake air and a fuel-reformer which has a fuel-reforming catalyst reforming fuel. The fuel-reformer is arranged downstream of the reforming-fuel injector. The reformed fuel is introduced into an intake pipe.
If a malfunction occurs in the fuel-reformer, it is likely that a combustion condition of the engine may be deteriorated. Thus, such a malfunction should be detected as early as possible.
The fuel-property reforming apparatus shown in JP-2007-113420A has a temperature sensor which detects temperature of the fuel-reforming catalyst. If the detected temperature of the fuel-reforming catalyst becomes out of a specified temperature range, the computer determines that the fuel-reformer has a malfunction.
It should be noted that a reforming-fuel injector may have a malfunction as well as the fuel-reformer. However, in the fuel-property reforming apparatus shown in JP-2007-113420A, a malfunction of the reforming-fuel injector can not be detected.